JP5949251B2 - Moving member detection apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a moving member detection device and an image forming apparatus including the moving member detection device.

  An electrophotographic color image forming apparatus such as a copying machine or a printer has four photoconductors corresponding to toners of four colors (yellow, cyan, magenta, black) in order to meet the recent demand for higher speed. A so-called tandem system in which (latent image carriers) are arranged side by side has become mainstream.

  In such a tandem system, each color toner image is sequentially transferred from a photoconductor of each color onto a sheet-like recording medium conveyed by a transfer belt as a moving member, or each color from a photoconductor of each color. Are sequentially transferred onto an intermediate transfer belt as a moving member, and then a full-color toner image is transferred from the intermediate transfer belt onto a sheet-like recording medium in a lump by using an intermediate transfer method. The toner images of the respective colors developed above are transferred onto a sheet-like recording medium (for example, paper, a postcard, an OHP (Overhead projector) sheet, etc.).

  In the direct transfer method, color misregistration occurs unless the conveyance belt that conveys the sheet-like recording medium is driven with high accuracy. In the intermediate transfer method, color misregistration occurs unless the intermediate transfer belt is driven with high accuracy. Resulting in.

  For this reason, in order to drive the intermediate transfer belt with high accuracy, the speckle pattern of the laser beam that is scanned on the intermediate transfer belt is received by a solid-state image sensor such as a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor). At the same time, the chronological change of the speckle pattern on the intermediate transfer belt is correlated to calculate the XY direction of the intermediate transfer belt (the X direction is the moving direction of the intermediate transfer belt and the Y direction is a direction perpendicular to the X direction). A displacement detection device that detects a displacement in a so-called in-plane direction is known (for example, see Patent Document 1).

  In order to prevent meandering of the intermediate transfer belt, a sensor such as a photo interrupter provided with a light emitting portion and a light receiving portion facing each other is disposed at an end portion parallel to the moving direction of the intermediate transfer belt, and the sensor There is known a meandering correction device that drives a meandering correction roller based on an end detection signal from the sensor to correct meandering of an intermediate transfer belt (see, for example, Patent Document 2).

  However, in the conventional displacement detection device disclosed in Patent Document 1, the vector in the direction orthogonal to the movement direction (X direction) of the intermediate belt (Y direction) is also generated even when the tension posture of the intermediate transfer belt is changed. Therefore, the detected vector component in the Y direction is a combination of the component in which the intermediate transfer belt approaches the Y direction and the angle at which the intermediate transfer belt is stretched around the roller. Detects the vector where the intermediate transfer belt moves in the Y direction even if the intermediate transfer belt moves around without moving in the Y direction when the angle of the belt stretched around the roller is not right angle There was a problem of doing.

  For this reason, if the position of the intermediate transfer belt that moves around without moving in the Y direction is adjusted based on the detected vector that moves in the Y direction, the toner image transferred onto the intermediate transfer belt is adjusted. There is a possibility that the transfer position of the image is shifted.

  In addition, when the mounting angle of the solid-state imaging device is tilted from the original angle, the intermediate transfer belt detects a vector that approaches the Y direction, so that erroneous control is performed, and the intermediate transfer belt falls off the roller. Or it may be too close to the Y direction and damage surrounding parts.

  Further, in the conventional meandering correction device disclosed in Patent Document 2, the photointerrupter is affected by the orthogonality of the end of the intermediate transfer belt, and the received light amount of the phototransistor constituting the photointerceptor of the photointerrupter is increased or decreased. Accordingly, the end of the intermediate transfer belt is detected, so that there is a limit in detecting the amount of displacement of the intermediate transfer belt in the Y direction with high definition.

  For this reason, in the image forming apparatus in which the conventional displacement detection device shown in Patent Document 1 or the conventional meandering correction device shown in Patent Document 2 is mounted, image position accuracy and position There is a limit to the improvement in alignment accuracy, and there is a limit to high-quality and high-quality image formation.

  The present invention aims to solve this problem. That is, the present invention can reduce the influence of the change in the tension posture of the moving member and reduce the influence of the change in the mounting posture of the solid-state imaging device, and can detect the displacement amount of the moving member with high definition. An object of the present invention is to provide a movable member detection device capable of forming a high-quality image with high accuracy.

  In order to solve the above problems and achieve the object, the moving member detection device of the present invention includes a light source for irradiating the moving member with coherent light, a solid-state imaging device capable of acquiring a two-dimensional image, and the light source. An imaging optical system that forms an image on the solid-state image sensor with a speckle pattern when the moving member is irradiated with coherent light, and an image is formed on the solid-state image sensor at regular time intervals as the moving member moves. A moving member comprising: an image pattern acquiring unit that acquires the speckle pattern as an image pattern; and a speed calculating unit that calculates the speed of the moving member by calculating the image pattern acquired by the image pattern acquiring unit. In the detection device, the solid-state imaging device serves as a detection region at an end of the moving member that is substantially parallel to the moving direction of the moving member. Is urchin arranged, is characterized in that the edge detecting means for detecting the end of the moving member by calculating an image pattern acquired by the image pattern acquisition means.

  In the moving member detection device of the present invention, the solid-state imaging device is arranged so that the end of the moving member becomes the detection region, and the end is detected by calculating the image pattern acquired by the image pattern acquisition unit. By providing the edge detecting means for performing the processing, the speckle pattern and the end on the moving member can be acquired as an image pattern, and the displacement of the moving member can be detected from the displacement of the speckle pattern. The tension posture of the moving member can be detected from the displacement of the end portion.

  For this reason, it is assumed that the vector in which the speckle pattern approaches the orthogonal direction (Y direction) perpendicular to the moving direction (X direction) of the moving member due to a change in the mounting posture of the solid-state imaging device is detected. However, when the moving member is moved without moving in the Y direction, the displacement of the end portion in the image pattern is not detected, so that the position of the moving member is prevented from being unnecessarily adjusted. Can do.

  Further, when the mounting posture of the solid-state imaging device is changed, a vector in which the speckle pattern approaches the orthogonal direction (Y direction) perpendicular to the moving direction (X direction) of the moving member is detected. When is moving in the Y direction, the displacement of the end of the image pattern is detected, so that the position of the moving member can be adjusted.

  Moreover, since the speckle pattern is sufficiently fine and the displacement of the moving member is detected from the displacement of the speckle pattern, the displacement amount of the moving member can be detected with high definition.

  Accordingly, since the displacement amount of the transfer belt or the intermediate transfer belt as the moving member in the image forming apparatus can be detected with high accuracy by the moving member detection device of the present invention, the moving member can be controlled with high precision and accuracy. High quality images can be formed.

1 is a schematic diagram of an image forming apparatus according to a first embodiment of the present invention. It is a figure for demonstrating the structure of the moving member detection apparatus provided in the image forming apparatus shown in FIG. It is a schematic diagram of the circuit of the speed calculation means of the moving member detection apparatus shown in FIG. FIG. 4 is a diagram illustrating a detection area on an intermediate transfer belt. (A) is a plan view and (B) is an enlarged view of a main part. It is a figure which shows the image pattern imaged by the area sensor. (A) is a figure which shows the last image pattern, (B) is a figure which shows the present image pattern. It is a figure which shows the image pattern imaged by the area sensor of the moving member detection apparatus concerning the 2nd Embodiment of this invention. (A) is a figure which shows the last image pattern, (B) is a figure which shows the present image pattern. It is a figure which shows the detection area on the intermediate transfer belt of the moving member detection apparatus concerning the 3rd Embodiment of this invention. (A) is a plan view and (B) is an enlarged view of a main part. It is the schematic of the image forming apparatus concerning the 4th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiments of the present invention described below are merely representative embodiments of the present invention, and the present invention is not limited to the embodiments. Therefore, the present invention can be implemented with various modifications without departing from the gist of the present invention, that is, those that can be easily assumed by those skilled in the art, substantially the same, and so-called equivalent ranges.

(First embodiment)
FIG. 1 is a schematic diagram of an image forming apparatus 30 according to the first embodiment of the present invention. FIG. 2 is a diagram for explaining the configuration of the moving member detection device 1 provided in the image forming apparatus 30. FIG. 3 is a schematic diagram of a circuit of the speed calculation unit 11. FIG. 4 is a diagram for explaining the detection area R0 on the intermediate transfer belt 2. FIG. FIG. 5 is a schematic diagram of the image pattern P acquired by the image pattern acquisition unit 9.

  The image forming apparatus 30 according to the first embodiment of the present invention is a copying machine, a printer, a facsimile, or a complex machine thereof, and is, for example, a tandem type full-color image forming apparatus. The image forming apparatus 30 records a toner image on a sheet-like recording medium such as paper, recording paper, transfer paper, or an OHP (Overhead projector) sheet.

  As shown in FIG. 1, the image forming apparatus 30 includes an optical scanning device 31 as a latent image forming unit, photosensitive drums 33Y to 33K as a latent image carrier, an intermediate transfer belt 2 as a moving member, and a primary. Transfer rollers 38 </ b> Y to 38 </ b> K, a secondary transfer roller 43, and a fixing device 47 are provided.

  The optical scanning device 31 receives the reflected light reflected from the document on the contact glass (not shown) and converts the electrical signal from the image sensor into an electrical signal, and the image processing means processes the electrical signal. A laser light emitting device that performs line scanning of laser light in the main scanning direction based on image data, and an fθ lens that condenses the laser light from the laser light emitting device and corrects the scanning speed in the main scanning direction to be constant. And a reflecting mirror that irradiates the respective photosensitive drums 33Y to 33K with laser light whose scanning speed in the main scanning direction is constant by the fθ lens.

  The laser light emitting device includes a light source composed of a semiconductor laser that emits laser light, and an optical deflector that deflects the laser light in the main scanning direction. The light source is provided with a semiconductor laser corresponding to each of yellow, cyan, magenta, and black, which are color separation components of a color image.

  The photosensitive drum 33Y includes a charging unit 35Y as a charging unit corresponding to yellow toner, a developing unit 36Y as a developing unit, and a cleaning device 37Y. The photosensitive drum 33C is a charging unit 35C corresponding to cyan toner. A developing device 36C and a cleaning device 37C. The photosensitive drum 33M includes a charging device 35M corresponding to magenta toner, a developing device 36M, and a cleaning device 37M. The photosensitive drum 33K corresponds to black toner. The charging device 35K, the developing device 36K, and the cleaning device 37K are provided.

  The photosensitive drums 33Y to 33K, the chargers 35Y to 35K, the developing devices 36Y to 36K, and the cleaning devices 37Y to 37K constitute a process unit that is detachably attached to the image forming apparatus 30.

  The photoconductor drums 33Y to 33K are made of, for example, a cylindrical aluminum base tube, and an organic photoconductor layer is provided on the outer peripheral surface of the aluminum base tube. On the photosensitive drums 33Y to 33K, electrostatic latent images are formed on the organic photosensitive layer by the laser beam scanned in accordance with the image forming signal, and toner as an unfixed image is formed by the developer of the developing units 36Y to 36K. An image is formed.

  The organic photoreceptor layer includes, for example, an undercoat layer coated on an outer peripheral surface of an aluminum base tube, a charge generation layer that generates both positive and negative charges by photoelectric conversion, and a positive charge generated in the charge generation layer. And a charge transport layer for neutralizing negative charges charged on the surface, and an overcoat layer for improving durability.

  The chargers 35Y to 35K are for uniformly charging the surfaces of the photosensitive drums 33Y to 33K. By applying a charging bias, the surfaces of the photosensitive drums 33Y to 33K are set to a desired polarity and a desired potential. A charging member for uniformly charging is provided. As the charging member, for example, a charging roller made of an elastic body, a scorotron charger having a wire electrode and a grid electrode, or the like can be used.

  The developing devices 36Y to 36K include a developer corresponding to each color, and a developing roller that is disposed to face the photosensitive drums 33Y to 33K and supplies toner onto the photosensitive drums 33Y to 33K.

  The developer 36Y contains a developer corresponding to yellow, which is a color separation component of a color image, and the developer 36C contains a developer, corresponding to cyan, which is a color separation component of a color image. The developer corresponding to magenta of the color separation component of the color image is accommodated, and the developer corresponding to black of the color separation component of the color image is accommodated in the developing device 36K.

  As the developer, for example, a two-component developer (including a case where an additive or the like is added) composed of a magnetic carrier and a nonmagnetic toner is used. The carrier and the toner are mixed in the casings of the developing units 36Y to 36K, so that the carrier is charged to the positive electrode and the toner is charged to the negative electrode. The carrier is formed, for example, by coating the surface of a fine powder such as iron or ferrite with an organic polymer.

  The toner includes, for example, transparent resin fine particles as an adhesive that is melted by heating, cyan (light blue) pigment, magenta (red purple) pigment, yellow (yellow) pigment, and black (black) pigment. Particles of any one of the above, fine particles of wax for suppressing the stickiness of the resin melted by heating, fine particles of a charge control agent for promoting frictional charging between the carrier and the toner, and adhesion between the particles And fine particles of an additive for suppressing the dispersion.

  As the developer, a magnetic toner can be used instead of the above-described configuration, and other known developers can be adopted.

  The developing roller includes a cylindrical magnet roller having a plurality of fixed magnetic poles, and a non-magnetic conductive cored bar that is externally attached to the magnet roller. The cored bar is made of, for example, a hollow aluminum base tube. In the developing roller, a region facing the photosensitive drums 33Y to 33K is a developing region.

  For this reason, the developing roller draws up the developer on the surface of the developing roller and rotates while being carried on the surface, and can carry the carried developer to the developing area facing the photosensitive drums 33Y to 33K.

  The developing roller is applied with a developing bias from a developing bias power source. For this reason, in the developing area, a potential difference is generated between the potential of the surface of the developing roller and the potential of the electrostatic latent image portion on the surface of the photosensitive drums 33Y to 33K, and the action of the developing electric field formed by this potential difference is caused. In response, the toner in the developer adheres to the electrostatic latent image.

  In this manner, by attaching toner from the developing roller to the electrostatic latent images on the photosensitive drums 33Y to 33K, the electrostatic latent images on the photosensitive drums 33Y to 33K become toner images as unfixed images.

  The cleaning devices 37Y to 37K are for removing residual transfer toner remaining on the surfaces of the photosensitive drums 33Y to 33K without being transferred onto the sheet-like recording medium from the surfaces of the photosensitive drums 33Y to 33K. The cleaning devices 37Y to 37K include blade members that scrape off and remove the transfer residual toner on the surfaces of the photosensitive drums 33Y to 33K.

  In addition to the untransferred toner, the blade member includes paper powder of the sheet-like recording medium, discharge products when the photosensitive drums 33Y to 33K are charged by the chargers 35Y to 35K, and additives added to the developer. Are removed from the photosensitive drums 33Y to 33K.

  Further, the blade member is made of, for example, a synthetic resin such as polyurethane resin, and is provided so as to be in a counter direction with respect to the rotation direction of the photosensitive drums 33Y to 33K, and the surface of the photosensitive drums 33Y to 33K. Is touching.

  The intermediate transfer belt 2 is an endless belt, and is stretched around a driving roller 39, a driven roller 40, and a tension roller 41. Further, the intermediate transfer belt 2 includes a belt cleaning device (not shown).

  The intermediate transfer belt 2 is a single layer or a plurality of layers such as, for example, vinylidene fluoride resin (PVDF resin), tetrafluoroethylene / ethylene copolymer resin (ETFE resin), polyimide resin (PI resin), polycarbonate resin (PC resin), or the like. A conductive material such as carbon black is dispersed.

  Further, a bias is applied to the intermediate transfer belt 2 with a polarity opposite to the polarity of the charge of the toner. For this reason, the toner image is transferred onto the intermediate transfer belt 2 by attracting the toner from the surface of the photosensitive drums 33Y to 33K to the intermediate transfer belt 2 side.

  The belt cleaning device includes a cleaning blade made of an elastic material such as urethane rubber that comes into contact with the intermediate transfer belt 2. The cleaning blade is detachably held by a swingable blade holder.

  The cleaning blade contacts the surface of the intermediate transfer belt 2 in a counter direction with respect to the circumferential direction of the intermediate transfer belt 2, and residual transfer toner on the surface of the intermediate transfer belt 2 is blocked and removed.

  As described above, since the cleaning blade comes into contact with the surface of the intermediate transfer belt 2, impurities such as paper powder of the sheet-like recording medium, additives added to the developer, and the like in addition to the transfer residual toner are present in the intermediate transfer belt. 2 is removed from the surface. Transfer residual toner or the like removed from the intermediate transfer belt 2 is collected by a toner collecting unit by a conveying unit provided in the belt cleaning device.

  The primary transfer rollers 38Y to 38K are disposed to face the photosensitive drums 33Y to 33K. The primary transfer rollers 38 </ b> Y to 38 </ b> K include a conductive shaft body and a conductive elastic body extrapolated to the conductive shaft body. A primary transfer nip is formed between the primary transfer rollers 38Y to 38K and the photosensitive drums 33Y to 33K.

  The primary transfer rollers 38Y to 38K are biased with a polarity opposite to the polarity of the charge on the photosensitive drums 33Y to 33K. Therefore, the toner is attracted from the surface of the photosensitive drums 33 </ b> Y to 33 </ b> K toward the intermediate transfer belt 2, and the toner image is primarily transferred onto the surface of the intermediate transfer belt 2.

  The conductive shaft is formed in a cylindrical bar shape, and is made of a metal such as stainless steel or aluminum. Note that the conductive shaft body may be made of a material having high mechanical strength and conductivity, such as carbon fiber, metal fiber, or a resin rod having a surface plated with metal.

  The conductive elastic body is formed in a cylindrical shape that is extrapolated to the conductive shaft body. For example, acrylonitrile butadiene rubber (NBR), ethylene / propylene / diene rubber (EPDM), chloroprene rubber (CR), etc. are carbon black. Sponge rubber to which a conductive material such as is added is used.

  The secondary transfer roller 43 is disposed to face the opposing roller 42 on which the intermediate transfer belt 2 is stretched, and a secondary transfer nip is formed between the secondary transfer roller 43 and the opposing roller 42. The secondary transfer roller 43 includes a conductive shaft and a conductive elastic body extrapolated to the conductive shaft.

  A bias is applied to the secondary transfer roller 43 with a polarity opposite to the polarity of the toner charge on the intermediate transfer belt 2. For this reason, the toner is attracted from the surface of the intermediate transfer belt 2 to the sheet-like recording medium side sandwiched by the secondary transfer nip, and the toner image is secondarily transferred onto the sheet-like recording medium.

  The conductive shaft body is made of a conductive metal similarly to the primary transfer rollers 38Y to 38K, and the conductive elastic body is made of a conductive sponge rubber like the primary transfer rollers 38Y to 38K. ing.

  Similar to the secondary transfer roller 43, the opposing roller 42 has a conductive shaft made of a conductive metal, and a conductive elastic made of a conductive sponge rubber that is extrapolated to the conductive shaft. And a body.

  The fixing device 47 heats and pressurizes a toner image as an unfixed image on a sheet-like recording medium and fixes it on the sheet-like recording medium. The fixing device 47 includes a fixing roller, and a pressure roller that is disposed to face the fixing roller and is pressed against the fixing roller to rotate the fixing roller. The fixing roller and the pressing roller are pressed against each other to form a fixing nip.

  The fixing roller is provided in the core metal, for example, a core metal formed in a cylindrical shape, an elastic layer that covers the outer peripheral surface of the core metal, a release layer that covers the outer peripheral surface of the elastic layer, and the like. And a heater as a heating source.

  The metal core is made of a known material such as a metal having high mechanical strength such as stainless steel or a carbon steel pipe for machine structure. The cored bar is formed wider (longer) than the sheet-like recording medium that passes through the fixing nip.

  The elastic layer is made of, for example, an elastic material such as silicone rubber, fluorine rubber, or foamable silicone rubber. The release layer is made of, for example, a fluororesin such as a tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin (PFA resin) or a tetrafluoroethylene resin (PTFE resin).

  As the heater, a known heating means such as a ceramic heater or a halogen heater is used. The output of the heater is controlled based on the surface temperature of the fixing roller detected by the temperature detection sensor, and the surface temperature of the fixing roller is held at a predetermined temperature.

  Similar to the fixing roller, the pressing roller includes a cored bar made of a metal having high mechanical strength, an elastic layer made of an elastic material, and a release layer made of a fluororesin. . The pressing roller is rotationally driven by a driving device such as a motor, and rotationally drives the fixing roller that is disposed opposite to and pressed against the pressing roller.

  The image forming apparatus 30 configured as described above further includes a moving member detection device 1 for detecting the moving speed and the displacement amount of the intermediate transfer belt 2 as a moving member, as shown in FIG.

  The moving member detection apparatus 1 includes a light source 4 that irradiates the surface of the intermediate transfer belt 2 with a laser beam 5 as coherent light, an area sensor 7 that can acquire the surface of the intermediate transfer belt 2 as a two-dimensional image, and an intermediate transfer. An image pattern acquisition means 9 for acquiring, as an image pattern (see FIG. 5) P, a speckle pattern (see FIG. 4B) S imaged on the area sensor 7 at regular time intervals as the belt 2 moves; By calculating the image pattern P acquired by the image pattern acquisition means 9, the speed calculation means 11 for calculating the speed and displacement of the intermediate transfer belt 2, and by calculating the image pattern P acquired by the image pattern acquisition means 9 An edge detection unit 13 as an edge detection unit that detects an end (see FIG. 4A) 2a of the intermediate transfer belt 2 and a drive roller 39 are provided. It includes and motor 17, for rotating the drive, a control unit 15 for controlling both the steering adjusting device 19 for adjusting the steering of the driven roller 40.

  The light source 4 includes a semiconductor laser element that emits a laser beam 5 that is coherent light, and a collimator lens that makes the laser beam 5 emitted from the semiconductor laser element substantially parallel light. The semiconductor laser element is set to an output that clearly forms a speckle pattern (see FIG. 4B) on the intermediate transfer belt 2.

  The area sensor 7 uses a solid-state imaging device that acquires the surface of the intermediate transfer belt 2 as a two-dimensional image and a speckle pattern S formed by the laser beam 5 irradiated on the surface of the intermediate transfer belt 2 as the solid-state imaging device. An imaging optical system (not shown) for forming an image.

  The area sensor 7 is arranged in parallel to the plane of the surface of the intermediate transfer belt 2. That is, the optical axis of the area sensor 7 is arranged so as to be orthogonal to the plane of the surface of the intermediate transfer belt 2. As shown in FIG. 4A, the area sensor 7 includes the end 2a that is substantially parallel to the moving direction of the intermediate transfer belt 2 (the direction indicated by the arrow t, that is, the X direction). A region on the surface of the belt 2 is set as a detection area R0 as a detection region of the area sensor 7.

  As the solid-state imaging device, for example, a CCD image sensor (Charge Coupled Device Image Sensor) or a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor) is used. The CMOS image sensor can be suitably used as a solid-state imaging device of the area sensor 7 because data processing in pixel units is obtained and image processing is easy.

  As shown in FIG. 2, the image pattern acquisition means 9 is a speckle pattern (see FIG. 4B) S that is imaged on the solid-state image sensor of the area sensor 7 at regular intervals as the intermediate transfer belt 2 moves. An image is entered.

  Further, the image pattern acquisition means 9 is not shown so that the speckle pattern image is formed (that is, exposed) at regular time intervals with the movement of the intermediate transfer belt 2 on the solid-state imaging device of the area sensor 7. A control signal for controlling opening and closing of the shutter device is output.

  Further, the image pattern acquisition unit 9 generates the speckle pattern S on the intermediate transfer belt 2 according to the moving speed of the intermediate transfer belt 2, the sensitivity of the solid-state imaging device, the intensity of the laser beam 5 emitted from the light source 4, and the like. The exposure time is controlled so that it can be clearly read by the solid-state imaging device.

  Further, the image pattern acquisition unit 9 uses the speckle pattern image acquired at regular time intervals as the intermediate transfer belt 2 moves as an image pattern (see FIG. 5A or FIG. 5B) P as a speed calculation unit 11. And the edge detection unit 13.

  As shown in FIG. 3, the speed calculation unit 11 includes a fast Fourier transform unit 21 that Fourier transforms an image pattern P that is a two-dimensional image output from the image pattern acquisition unit 9 at regular time intervals, and the fast Fourier transform unit. Among the results converted at 21, a memory 22 that deletes and stores a low-frequency region of the spatial frequency that is a background of an image that is not necessary for the correlation calculation of the speckle pattern S, and is stored in the memory 22. Read the result, replace the part deleted at the time of storage with 0, and convert it to a conjugate complex number, and the time corresponding to the result of the conjugate complex number conversion unit 23 and the result of the conjugate complex number conversion unit 23 A complex multiplier 24 that multiplies both of the results obtained by transforming the image patterns P adjacent to each other by the fast Fourier transform unit 21; and the complex multiplier 2 The inverse fast Fourier transform unit 25 that performs inverse Fourier transform on the result of the above, the peak position detection unit 26 that derives the correlation peak by sub-pixel processing the result of the inverse fast Fourier transform unit 25, and the derivation of the peak position detection unit 26 A vector decomposing unit 27 that vector-decomposes the correlation peak with respect to the moving direction (X direction) and the shifting direction (Y direction) of the intermediate transfer belt 2 and outputs the moving speed and displacement (skew) of the intermediate transfer belt 2; It is equipped with.

  That is, the speed calculation unit 11 stores the data of the image pattern P1 immediately before the time in the image pattern P adjacent to the time interval (see FIG. 4A) P1 in the memory 22, and the image pattern adjacent to the time interval. The data of the current temporal image pattern P2 (see FIG. 4B) P2 is compared with the data of the immediately preceding image pattern P1.

  Further, the speed calculation means 11 stores the current image pattern P2 in the memory 22 and compares it with data of an image pattern (not shown) immediately after in the adjacent image pattern P of the time interval. In this way, the image data are sequentially compared. Moreover, the speed calculation means 11 calculates | requires the position shift of the adjacent image pattern P of a time interval as a correlation peak position.

  Further, the speed calculation means 11 reduces the storage capacity by deleting the low frequency region of the spatial frequency that is the background of the image that is not necessary for the correlation calculation of the speckle pattern S and storing it in the memory 22. In addition, the number of executions of Fourier transform can be reduced and the calculation efficiency can be improved as compared with the case of storing without deleting.

  The edge detection unit 13 corresponds to a deletion unit that deletes a speckle pattern portion that is unnecessary for edge detection, and brightness on the image in the vicinity of the end portion (see FIG. 4B) 2a of the intermediate transfer belt 2. A projection waveform conversion unit that converts the shades into a projected waveform, a differential waveform conversion unit that differentially converts the projection waveform converted by the projection waveform conversion unit into a differential waveform, and the differential waveform conversion unit An edge output unit that outputs a peak point exceeding the threshold of the differential waveform as an edge.

  As described above, since the edge detection unit 13 detects the end 2a of the intermediate transfer belt 2, it is possible to separately calculate the image of the end 2a of the intermediate transfer belt 2 that causes noise for correlation calculation. Therefore, the accuracy of the speed calculation means 11 can be increased. The edge detection unit 13 may employ an edge detection circuit that can detect a known edge.

  The control unit 15 receives, for example, the speed signal and the displacement signal output from the speed calculation unit 11 and the edge signal output from the edge detection unit 13, and the speed signal, the displacement signal, and the edge signal. Is provided with a signal processing unit that generates a control signal.

  For this reason, when the intermediate transfer belt 2 is skewed (change in the stretching posture) due to the speed signal and the displacement signal output from the speed calculation unit 11 and the edge signal output from the edge detection unit 13. If it is determined, or if it is determined that a displacement in the shifting direction (Y direction) occurs with respect to the moving direction (X direction) of the intermediate transfer belt 2, or both skew and displacement occur. 2, when the control signal is output from the control unit 15, a steering adjustment device for adjusting the steering of the driven roller 40 on which the intermediate transfer belt 2 is stretched is provided. 19 and the motor 17 for driving the drive roller 39 that drives the intermediate transfer belt 2 to rotate are controlled, and the skew and displacement of the intermediate transfer belt 2 are eliminated.

  As the steering adjustment device 19, a known device such as a steering mechanism or a steering device that can adjust the steering of the driven roller 40 with respect to the intermediate transfer belt 2 can be adopted. Further, the image pattern acquisition unit 9, the speed calculation unit 11, the edge detection unit 13, and the control unit 15 may be configured by a one-chip microcomputer, for example.

  Next, the operation and processing in the image forming apparatus 30 according to the first embodiment of the present invention configured as described above will be described.

  As shown in FIG. 1, when the start key of the operation unit of the image forming apparatus 30 is pressed, the photosensitive drums 33Y to 33K corresponding to the respective colors of yellow, cyan, magenta, and black are rotationally driven. The surfaces of the body drums 33Y to 33K are uniformly charged to a predetermined polarity by the chargers 35Y to 35K.

  Further, the image information of the document on the contact glass is read by line scanning in the sub-scanning direction by an image reading device (not shown) and sent to the optical scanning device 31.

  The image information sent to the optical scanning device 31 is single-color image information obtained by separating the image information, which is a full-color image, into color information of yellow, cyan, magenta, and black by the image processing unit. Based on the image information, the laser beam is line-scanned in the main scanning direction, and the laser beams are irradiated onto the photosensitive drums 33Y to 33K corresponding to the respective colors.

  An electrostatic latent image corresponding to single-color image information of the original is formed on the photosensitive drums 33Y to 33K by the laser light emitted from the optical scanning device 31, and each color is supplied from the developing units 36Y to 36K corresponding to each color. Is supplied onto the photosensitive drums 33Y to 33K, and an unfixed toner image is formed from the electrostatic latent image.

  At this time, the intermediate transfer belt 2 and the primary transfer rollers 38Y to 38K are applied with a bias having a polarity opposite to the charging polarity of the toner of the unfixed toner images on the photosensitive drums 33Y to 33K, and the photosensitive drums 33Y to 33K. And an intermediate transfer belt 2 form a transfer electric field.

  The intermediate transfer belt 2 is rotated in the direction of the arrow t (clockwise in the drawing), and the toner images on the photosensitive drums 33Y to 33K are sequentially superimposed and transferred onto the intermediate transfer belt 2 by the transfer electric field. A full color toner image is formed on the belt 2.

  A sheet-like recording medium is fed from a paper cassette (not shown), and the timing is measured by a registration roller and is fed to the transfer nip of the secondary transfer roller 43 (arrow a).

  At this time, a bias having a polarity opposite to the charging polarity of the toner of the full-color toner image on the intermediate transfer belt 2 is applied to the secondary transfer roller 43, and between the intermediate transfer belt 2 and the secondary transfer roller 43. A transfer electric field is formed.

  Due to the transfer electric field, the full-color toner image on the intermediate transfer belt 2 is collectively transferred onto a sheet-like recording medium held in the transfer nip of the secondary transfer roller 43.

  At this time, transfer residual toner and the like remaining on the surfaces of the photosensitive drums 33Y to 33K are removed from the surfaces of the photosensitive drums 33Y to 33K by the cleaning devices 37Y to 37K. Further, the surfaces of the photosensitive drums 33Y to 33K are subjected to a charge removing action from the charge removing device, and the surface potential thereof is initialized to prepare for the next image formation.

  Further, residual toner remaining on the surface of the intermediate transfer belt 2 is removed from the surface of the intermediate transfer belt 2 by a belt cleaning device.

  The sheet-like recording medium to which the full-color toner image has been transferred is conveyed to the fixing device 47 by the conveying device 45, and heat and pressure are applied to the sheet-like recording medium to fix the full-color toner image.

  The sheet-like recording medium on which the full-color toner image is fixed is discharged to a discharge tray (not shown) of the image forming apparatus 30 and stacked on the discharge tray.

  At this time, the moving speed and displacement of the intermediate transfer belt 2 are detected by the moving member detecting device 1 shown in FIG. As shown in FIG. 4A, a laser beam (see FIG. 1) 5 is irradiated from the light source 4 to the detection area R0 including the end 2a of the intermediate transfer belt 2, and as shown in FIG. A speckle pattern S that is scattered light of the laser beam 5 is formed on the surface of the transfer belt 2.

  The speckle pattern S formed in the detection area R0 is aread at regular time intervals as the intermediate transfer belt 2 moves by a shutter device that repeatedly opens and closes at regular time intervals under the control of the image pattern acquisition means (see FIG. 1) 9. The image is formed on the solid-state image sensor of the sensor 7 and sent to the image pattern acquisition means 9 as an image pattern P.

  Specifically, as shown in FIG. 5A, the image pattern P1 immediately before in the adjacent image pattern P at a fixed time interval is captured by the solid-state imaging device, and the image pattern P1 is transferred to the image pattern acquisition unit 9. Then, the temporal current image pattern P2 in the adjacent image patterns P at a fixed time interval is captured by the solid-state imaging device, and the image pattern P2 is sent to the image pattern acquisition means 9.

  The adjacent image patterns P with a fixed time interval sent to the image pattern acquisition unit 9 in this way are sequentially sent to the speed calculation unit 11 and the edge detection unit 13 as shown in FIG.

  5A and 5B schematically show an image pattern P1 captured by a solid-state imaging device having a resolution of 6 pixels × 6 pixels, and the present invention is not limited to this. is not.

  In the speed calculation means 11, after the image data of the immediately preceding image pattern P1 is stored in the memory 22, it is compared with the image data of the current image pattern P2 to detect the moving speed and displacement. Further, the edge detection unit 13 stores the image data of the immediately preceding image pattern P1 in the storage unit, and then compares it with the image data of the development image pattern P2 to detect the deviation of the end 2a (Y direction deviation). Is done.

  Specifically, for example, when an image pattern P as shown in FIGS. 5A and 5B is obtained, a speckle pattern in the current image pattern P2 with respect to the immediately preceding image pattern P1. The displacement of S is represented by a vector indicated by an arrow e, and the positional deviation of the end 2a is represented by a deviation indicated by an arrow f (deviation in the Y direction).

  That is, when the image pattern P as shown in FIGS. 5A and 5B is obtained, the vector indicated by the arrow e of the speckle pattern S includes a component in the Y direction (side). In addition, since the end 2a is displaced (deviated) indicated by the arrow f, the intermediate transfer belt 2 is not affected by the change in the mounting posture of the area sensor (see FIG. 1) 7. It can be determined that there is a deviation.

  Even if the mounting posture of the area sensor 7 is tilted from a predetermined position, the component in the Y direction of the speckle pattern S is used when the intermediate transfer belt 2 is circulated without any deviation. Although the included vector is confirmed, since the inclination of the end portion 2a on the image pattern P corresponding to the inclination of the area sensor 7 does not change, it can be determined that no deviation of the intermediate transfer belt 2 has occurred, It is possible to prevent unnecessary adjustment of the intermediate transfer belt 2.

  In addition, when the intermediate transfer belt 2 is rotated in a state where the mounting posture of the area sensor 7 is inclined from a predetermined position and the deviation occurs, the vector including the Y-direction component of the speckle pattern S And the deviation of the inclination of the end portion 2a on the image pattern P in the Y direction can be confirmed, so that it can be determined that the intermediate transfer belt 2 is deviated. 2 can be adjusted appropriately.

  In this way, by observing the displacement of the speckle pattern S and the displacement of the end portion 2a of the intermediate transfer belt 2, it is possible to detect a change in the inclination of the tension posture of the intermediate transfer belt 2, so that each color can be detected. By detecting the tension posture that is an error component for toner image superposition (color superposition), and controlling the tension posture and adjusting the output image, high accuracy without color misregistration is achieved. A full color image can be obtained.

  In addition, since the image of the end 2a of the intermediate transfer belt 2 that is a noise component and the image of the speckle pattern S are separately calculated for the correlation calculation, the detection accuracy of both the end 2a and the speckle pattern S is improved. Can be increased.

  Further, since the movement speed of the intermediate transfer belt 2 and the movement (displacement) in the shift direction (Y direction) are simultaneously measured, the rotational speed adjustment of the motor 17 is controlled based on the difference in the target speed of the movement speed. The moving speed can be controlled to be constant.

  Further, since the steering control is performed based on the measurement result of the shift position, the position in the shift direction can be controlled to be kept constant.

  Therefore, by controlling the moving speed of the intermediate transfer belt 2 to be constant and controlling so that the position in the shift direction does not change, a high-quality full-color toner having no positional deviation or color deviation on the intermediate transfer belt 2 is obtained. The image can be carried, and the accuracy of the output image output from the image forming apparatus 30 can be improved.

  As described above, the moving member detection apparatus 1 according to the first embodiment of the present invention can acquire the light source 4 for irradiating the intermediate transfer belt 2 with the laser beam 5 and the two-dimensional image. Area sensor 7, an imaging optical system that forms an image on speckle pattern S when laser beam 5 is irradiated from intermediate light source 4 onto intermediate transfer belt 2, and intermediate transfer belt 2, the image pattern acquisition means 9 for acquiring the speckle pattern S imaged on the area sensor 7 at regular time intervals as the image pattern P and the image pattern P acquired by the image pattern acquisition means 9 are calculated. And a speed calculating means 11 for calculating the speed of the intermediate transfer belt 2, wherein the area sensor 7 includes the area sensor 7. The end 2a of the intermediate transfer belt 2 that is substantially parallel to the moving direction X of the intermediary transfer belt 2 is arranged to be the detection area R0, and the image pattern P acquired by the image pattern acquisition means 9 is calculated. Thus, an edge detecting means 13 for detecting the end 2a of the intermediate transfer belt 2 is provided.

  As described above, the area sensor 7 is arranged so that the end 2a of the intermediate transfer belt 2 becomes the detection area R0, and the end 2a is calculated by calculating the image pattern P acquired by the image pattern acquisition means 9. Is provided, the speckle pattern S and the end portion 2a on the intermediate transfer belt 2 can be acquired as the image pattern P, and the intermediate transfer can be performed from the displacement of the speckle pattern S. The displacement of the belt 2 can be detected, and the tension posture of the intermediate transfer belt 2 can be detected from the displacement of the end 2a.

  For this reason, even if a vector in which the speckle pattern S approaches the orthogonal direction Y perpendicular to the moving direction X of the intermediate transfer belt due to a change in the mounting posture of the area sensor 7 is detected, the intermediate transfer is performed. When the belt 2 is circulated without moving in the orthogonal direction Y, the displacement of the end 2a in the image pattern P is not detected, so that the tension posture (steering) of the intermediate transfer belt 2 is unnecessarily adjusted. Can be prevented.

  Further, when the mounting posture of the area sensor 7 is changed, a vector in which the speckle pattern S approaches the orthogonal direction Y perpendicular to the moving direction X of the intermediate transfer belt 2 is detected. When approaching the orthogonal direction Y, the displacement of the end 2a in the image pattern P is detected, so that the stretching posture (steering) of the intermediate transfer belt 2 can be adjusted appropriately.

  Further, since the speckle pattern S is sufficiently fine and the displacement of the intermediate transfer belt 2 is detected from the displacement of the speckle pattern S, the displacement amount of the intermediate transfer belt 2 can be detected with high definition.

  Moreover, since the moving member detection apparatus 1 according to the first embodiment of the present invention stores the image information for comparison when performing the correlation calculation in the memory 22 as data after the Fourier transform processing, The calculation load can be reduced compared to the case where the image information is subjected to Fourier transform processing.

  In addition, the moving member detection apparatus 1 according to the first embodiment of the present invention causes the two-dimensional image to be subjected to the fast Fourier transform process and stores the data relating only to the speckle pattern S portion in the memory 22. Compared with the case where all the information is stored in the memory 22, the storage area of the memory 22 can be reduced.

  In addition, the image forming apparatus 30 according to the first embodiment of the present invention includes photosensitive drums 33Y to 33K on which electrostatic latent images are carried, and chargers 35Y to 35K that charge the photosensitive drums 33Y to 33K. An optical scanning device 31 that forms electrostatic latent images on the photosensitive drums 33Y to 33K, developing devices 36Y to 36K that develop the electrostatic latent images with toner to form toner images, and the toner images And the movement speed and displacement of the intermediate transfer belt 2 are detected by the moving member detecting device 1 described above, so that the movement speed and displacement amount of the intermediate transfer belt 2 are increased. Since it can be detected with high accuracy, the intermediate transfer belt 2 can be controlled with high definition, and a high-quality image with high accuracy can be formed.

(Second Embodiment)
Next, a moving member detection apparatus 1 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 schematically shows an image pattern P imaged by the area sensor 7. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, by using the origin signal generated by the origin signal generator once per rotation (one cycle) of the intermediate transfer belt 2, the first rotation image and the second rotation image and the like are compared and calculated. Detecting the shifting direction (Y direction) of the intermediate transfer belt 2 is different from the moving member detection apparatus 1 according to the first embodiment.

  Specifically, for example, one reflection mark is provided on the surface of the intermediate transfer belt 2, the reflection mark is read by an optical sensor, the shutter device is driven based on a detection signal output from the optical sensor, and circulates. An image pattern P is acquired for each rotation of the intermediate transfer belt 2, and as shown in FIGS. 6A and 6B, the current image pattern P2 and the previous image pattern P1 (that is, one rotation before) are obtained. Correlation is calculated, and the displacement for each rotation of the intermediate transfer belt 2 is detected.

  That is, in this embodiment, when the moving speed of the intermediate transfer belt 2 is precisely controlled, the displacement of the intermediate transfer belt 2 (change in the hanging posture) is detected.

  In the moving member detection apparatus 1 according to the second embodiment of the present invention configured as described above, as shown in FIGS. 6 (A) and 6 (B), the optical sensor from the optical sensor that detects the reflection mark is used. After the previous image pattern P1 is acquired based on the detection signal, the intermediate transfer belt 2 is rotated once and the current image pattern P2 is acquired based on the detection signal from the optical sensor that has detected the reflection mark.

  In FIGS. 6A and 6B, the speckle pattern S acquired in the second rotation is one pixel above the speckle pattern S1 acquired in the first rotation. An example of misalignment is shown.

  When the correlation calculation between the previous image pattern P1 acquired by the image pattern acquisition means 9 via the area sensor 7 and the current image pattern P2 is performed, a deviation is detected in the moving direction (X direction) of the intermediate transfer belt 2. Only the component in the shift direction (Y direction) is detected.

  Since the detected information at this time does not include the influence of the inclination of the tension posture of the intermediate transfer belt 2, the deviation of the intermediate transfer belt 2 can be accurately detected.

  Note that measurement without error can be performed similarly by detecting the edge of the end portion 2a of the intermediate transfer belt 2 without performing correlation calculation. In such a case, image information before one rotation is obtained. It is not necessary to memorize.

  As described above, the moving member detection apparatus 1 according to the second embodiment of the present invention has the image pattern P at the same location on the intermediate transfer belt 2 for each cycle of the circular movement of the intermediate transfer belt 2. And the shift direction Y of the intermediate transfer belt 2 is detected by comparing the position of each cycle of the intermediate transfer belt 2 in each cycle. A shift can be detected.

  Further, the steering adjustment is performed based on the detection information of the shift of the intermediate transfer belt 2 detected every cycle, and the hanging posture of the intermediate transfer belt 2 can be adjusted appropriately.

  Further, since the displacement of the intermediate transfer belt 2 is detected every one cycle, the load of the correlation calculation process can be greatly reduced.

  Further, the moving member detection apparatus 1 according to the second embodiment of the present invention has a reflection mark for generating a signal for each cycle of movement of the intermediate transfer belt 2 with respect to the origin position of the intermediate transfer belt 2. Therefore, an image pattern P1 including the same portion of the intermediate transfer belt 2 can be acquired every rotation of the intermediate transfer belt 2.

  In this way, since the image pattern P1 including the same portion of the intermediate transfer belt 2 can be obtained for each rotation of the intermediate transfer belt 2, only the component in the direction of the intermediate transfer belt 2 in the shift direction (Y direction) is obtained. Can be detected.

(Third embodiment)
Next, a moving member detection apparatus 1 according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram showing detection areas R0 to R3 on the intermediate transfer belt 2. As shown in FIG. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, the detection area R0 detected by the area sensor 7 every rotation of the intermediate transfer belt 2 provided with the reflection mark for generating the origin signal, and the detection area R0 to the fourth detection area R3. By comparing with the speckle pattern S stored in advance, the shift direction of the intermediate transfer belt 2 is adjusted based on a wide range of speckle patterns S in the shift direction (Y direction) of the intermediate transfer belt 2. This is different from the moving member detection apparatus 1 according to the second embodiment.

  Specifically, as shown in FIG. 7A, the speckles of the detection area R0 in which the end 2a of the intermediate transfer belt 2 that is the same location with respect to the moving direction X every rotation by the reflection mark is included in the detection region. A pattern S, a speckle pattern S of the second detection area R1 adjacent above the detection area R0, a speckle pattern S of the third detection area R2 adjacent above the second detection area R1, The speckle pattern S of the fourth detection area R3 adjacent above the third detection area R2 is stored in advance in the memory (see FIG. 3) 22 of the speed calculation unit 11.

  That is, the range from the detection area R0 to the fourth detection area R3 adjacent to each other is the shift detection range W of the intermediate transfer belt 2, and the intermediate transfer belt 2 in the shift detection range W is shown in FIG. The upper speckle pattern S is stored in the memory 22.

  For this reason, the speckle pattern S in the deviation detection range W on the intermediate transfer belt 2 and the speckle pattern S in the detection area R0 detected every rotation of the intermediate transfer belt 2 are subjected to correlation calculation. The displacement of the intermediate transfer belt 2 can be detected.

  In this manner, the speckle pattern S in the shift detection range W and the speckle pattern S in the detection area R0 can be subjected to correlation calculation to detect the displacement of the intermediate transfer belt 2, so that the detection area R0 can be detected. It is possible to enlarge the detection area as compared with the case where only the data is stored in the memory 22.

  For this reason, when the number of pixels of the area sensor 7 is increased and the detection area is enlarged, there is a problem that the storage area of the memory increases as the number of pixels increases. An increase in the storage area can be suppressed by the moving member detection apparatus 1 according to the third embodiment.

  Further, when the imaging magnification of the imaging optical system of the area sensor 7 is lowered and the detection area is enlarged, there is a problem that the detection resolution is lowered. However, the third embodiment of the present invention has a problem. Such a moving member detection device 1 can prevent a decrease in detection and decomposition.

  When acquiring the speckle pattern S in the deviation detection range W on the intermediate transfer belt 2 as a reference image, for example, the speckle pattern S in the detection area R0 including the end 2a of the intermediate transfer belt 2 is acquired. Thereafter, a desired shift is generated in the intermediate transfer belt 2 by the steering adjustment device 19, and the speckle pattern S in the second detection area R1, the speckle pattern S in the third detection area R2, and the speckle pattern in the fourth detection area R3. S is acquired sequentially.

  At this time, as shown in FIG. 7A, an overlapping portion B1 between the detection area R0 and the second detection area R1 is formed, and an overlapping portion B2 between the second detection area R1 and the third detection area R2 is formed. Then, an image is picked up by the area sensor 7 so that a part of the detection areas overlap each other so that an overlapping part B3 between the third detection area R3 and the fourth detection area R4 is formed.

  When each speckle pattern S from the detection area R0 to the fourth detection area R3 has been captured, the operation is shifted to an actual operation for image formation, and adjustment is performed by the steering adjustment device 19 so that the shift of the intermediate transfer belt 2 does not occur. .

  In actual operation, for example, when the speckle pattern S of the detection area R0 captured by the area sensor 7 is compared with the speckle pattern S of the detection area R0 stored in the memory 22, there is no correlation. A correlation between the speckle pattern S in the second detection area R1, the speckle pattern S in the third detection area R2, and the speckle pattern S in the fourth detection area R3 is sequentially performed, and the position of the intermediate transfer belt 2 is specified.

  When the shift position is specified, intermediate transfer is performed by the steering adjustment device 19 so that the speckle pattern S in the specified detection areas R1 to R3 and the speckle pattern S of the detection area R0 imaged by the area sensor 7 are matched. Adjust the belt 2 offset.

  As described above, by storing the speckle patterns S of the areas R0 to R4 as a plurality of reference images, it is possible to suppress a decrease in detection resolution and an increase in the load of calculation processing, and a shift detection range W Can be enlarged to an arbitrary size.

  The shift detection range W can be expanded more than the range of the detection area R0 to the fourth detection area R3, and is not limited to the illustrated example.

  As described above, the moving member detection apparatus 1 according to the third embodiment of the present invention uses a plurality of sheets in the offset direction Y of the intermediate transfer belt 2 as the image information of the origin position of the intermediate transfer belt 2. Since the image information is stored, the resolution of the area sensor 7 can be prevented from being lowered, and the shift detection range W of the intermediate transfer belt 2 can be expanded to an arbitrary size without increasing the load of correlation calculation processing. Can do.

(Fourth embodiment)
Next, an image forming apparatus 30 according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a schematic configuration diagram of the image forming apparatus 30. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, the transfer belt 2A is used as the moving member, and the toner images are sequentially superimposed from the photosensitive drums 33Y to 33K on the sheet-like recording medium conveyed by the transfer belt 2A. This is different from the image forming apparatus 30 according to the embodiment.

  Specifically, as shown in FIG. 8, the transfer belt 2 </ b> A stretched around the drive roller 39 and the driven roller 40 is an endless belt, and is the first to third embodiments described above. The shift position is adjusted by the moving member detection device 1 in FIG.

  Similarly to the intermediate transfer belt 2 described above, the transfer belt 2A is composed of a single layer or a plurality of layers such as PVDF resin, ETFE resin, PI resin, and PC resin, and a conductive material such as carbon black is dispersed therein. The surface of the transfer belt 2A is cleaned by a belt cleaning device (not shown).

  The transfer belt 2A is biased with a polarity opposite to the polarity of the charge of the toner. For this reason, the toner image is transferred onto the sheet-like recording medium conveyed by the transfer belt 2A by attracting the toner from the surface of the photosensitive drums 33Y to 33K to the transfer belt 2A side.

  As described above, the image forming apparatus 30 is a so-called direct transfer system in which the toner image is transferred from the photosensitive drums 33Y to 33K onto the sheet-like recording medium conveyed by the transfer belt 2A.

  As described above, in the image forming apparatus 30 according to the fourth embodiment of the present invention, in the direct transfer type image forming apparatus, the transfer belt 2A is shifted by the moving member detecting device 1 described above. Since it is adjusted, both the moving speed and displacement of the transfer belt 2A can be detected with high accuracy.

  Further, by detecting both the moving speed and displacement of the transfer belt 2A with high accuracy, the transfer belt 2A can be controlled with high definition, and a high-quality image with high accuracy can be formed.

  The image forming apparatus 30 described above may be a four-cycle full-color image forming apparatus that transfers each color of yellow, cyan, magenta, and black onto a sheet-like recording medium with a single photosensitive drum.

  The basic operation of the image forming apparatus 30 is an image forming operation when a full-color image is formed on a sheet-like recording medium, and is monochrome using one of the photosensitive drums 33Y to 33K corresponding to each color. An image may be formed, or a two-color or three-color image may be formed using two or three photosensitive drums 33Y to 33K.

  Further, the image forming apparatus 30 can be applied to various image forming apparatuses such as a copying apparatus, a printer, a facsimile, and a plotter as an image forming apparatus to which the present invention can be applied.

  Moreover, although the moving member detection apparatus 1 demonstrated the intermediate transfer belt 2 or the transfer belt 2A as a moving member, an endless belt-like member or a drum-like member can be adopted.

DESCRIPTION OF SYMBOLS 1 Moving member detection apparatus 2 Intermediate transfer belt (moving member)
2a, 2b End 2A Transfer belt (moving member)
4 Light source 5 Laser beam (coherent light)
7 Area sensor (solid-state image sensor)
9 Image pattern acquisition means 11 Speed calculation means 13 Edge detection unit (edge detection means)
DESCRIPTION OF SYMBOLS 15 Control part 17 Motor 19 Steering adjustment apparatus 22 Memory (memory | storage means)
30 Image forming device 31 Optical scanning device (latent image forming means)
33 Photosensitive drum (latent image carrier)
35 Charger (charging means)
36 Developer (Developer)
P Image pattern P1 Previous image pattern P2 Current image pattern R0 Detection area (detection area)
R1 Second detection area (detection area)
R2 Third detection area (detection area)
R3 4th detection area (detection area)
S speckle pattern W shift detection range X movement direction Y shift direction

JP 2009-15240 A JP-A-6-56295

Claims (6)

A light source for irradiating the moving member with coherent light, a solid-state imaging device capable of acquiring a two-dimensional image, and a speckle pattern when the moving member is irradiated with coherent light from the light source. An imaging optical system that forms an image on an image sensor, an image pattern acquisition unit that acquires the speckle pattern that is imaged on the solid-state image sensor at regular time intervals as the moving member moves, and the image pattern A speed calculating means for calculating the speed of the moving member by calculating the image pattern acquired by the acquiring means,
The solid-state imaging device is disposed so that an end portion of the moving member that is substantially parallel to the moving direction of the moving member serves as a detection region,
An apparatus for detecting a moving member, comprising: edge detecting means for detecting the end of the moving member by calculating an image pattern acquired by the image pattern acquiring means.   For each cycle of movement of the moving member, an image pattern of the same location of the moving member is acquired, and a position of the moving member for each cycle is compared to detect a shift direction of the moving member. The moving member detection apparatus according to claim 1.   3. The moving member detection device according to claim 2, further comprising an origin signal generating means for generating a signal for each cycle of movement of the moving member with respect to the origin position of the moving member.   The moving member detection according to any one of claims 1 to 3, wherein a plurality of pieces of image information in a direction close to the moving member is stored as image information of an origin position of the moving member. apparatus.   5. The moving member detection apparatus according to claim 1, wherein image information for comparison when performing the correlation calculation is stored in the storage unit as data after Fourier transform processing. 6. . A latent image carrier on which an electrostatic latent image is carried, charging means for charging the latent image carrier, latent image forming means for forming an electrostatic latent image on the latent image carrier, and the electrostatic latent image Developing means for developing the image with toner to form a toner image, a moving member to which the toner image is transferred,
In an image forming apparatus having a moving member detection device that detects a moving speed and displacement of the moving member,
The moving member is the moving member according to any one of claims 1 to 5,
The moving member detection device is the moving member detection device according to any one of claims 1 to 5,
An image forming apparatus, wherein the moving member is a transfer belt or an intermediate transfer belt.

Images